Enhancement of Dielectric Properties in 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3 Ceramics by Optimizing Sintering Temperature

Lead-free 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3(abbreviated as 0.98KNN-0.02LF) ceramics were prepared by a conventional solid-state sintering method at various sintering temperatures of 1140,1145,1150,1155 and 1160 ℃ and dwell time for 2 h.The samples were characterized by X-ray diffraction and scanning electron microscopy,respectively.The dielectric properties of the 0.98KNN-0.02 LF ceramics were also investigated.The results show that all the ceramics sintered at different sintering temperatures are a pure pseudo-cubic perovskite phase,and it is effective to improve the density and dielectric properties when the sintering temperature increases.However,the properties of the ceramics can be deteriorated when the sintering temperature exceeds the optimum value.The 0.98KNN-0.02 LF ceramics sintered at1150 ℃ for 2 h show the optimum dielectric properties,i.e.,the high dielectric permittivity(near 2000) and low dielectric loss(<5%) in the temperature range of 100-400 ℃ and the capacitance variation(AC/C_(150℃)) of ±15%,indicating a potential application in high-temperature ceramics capacitors.

Lead-free 0.98(K0.5Na0.5)NbO3-0.02LaFeO3(abbreviated as 0.98KNN-0.02LF) ceramics were prepared by a conventional solid-state sintering method at various sintering temperatures of 1140, 1145, 1150, 1155 and 1160℃ and dwell time for 2 h. The samples were characterized by X-ray diffraction and scanning electron microscopy, respectively. The dielectric properties of the 0.98KNN-0.02LF ceramics were also investigated. The results show that all the ceramics sintered at different sintering temperatures are a pure pseudo-cubic perovskite phase, and it is effective to improve the density and dielectric properties when the sintering temperature increases. However, the properties of the ceramics can be deteriorated when the sintering temperature exceeds the optimum value. The 0.98KNN-0.02LF ceramics sintered at 1150℃ for 2 h show the optimum dielectric properties,i.e., the high dielectric permittivity (near 2000) and low dielec-tric loss (<5%) in the temperature range of 100–400℃ and the capacitance variation (ΔC/C150℃) of ±15%, indicating a potential application in high-temperature ceramics capacitors.